Imaging lens

ABSTRACT

An imaging lens which uses a larger number of constituent lenses for higher performance and features compactness and a wide field of view. The imaging lens is composed of seven lenses to form an image of an object on a solid-state image sensor. The constituent lenses are arranged in the following order from an object side to an image side: a first lens with positive refractive power; a second lens with positive or negative refractive power; a third lens with negative refractive power; a fourth lens with positive or negative refractive power as a double-sided aspheric lens; a meniscus fifth lens having a convex surface on the image side; a sixth lens with positive or negative refractive power as a double-sided aspheric lens; and a seventh lens with negative refractive power, in which an air gap is provided between lenses.

The present application is based on and claims priority of Japanesepatent application No. 2013-188413 filed on Sep. 11, 2013, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to imaging lenses which form an image ofan object on a solid-state image sensor such as a CCD sensor or a C-MOSsensor used in a compact image pickup device. More particularly, theinvention relates to imaging lenses which are built in image pickupdevices mounted in highly functional products such as smart TVs and 4KTVs, information terminals such as game consoles and PCs, and mobileterminals such as smart phones, mobile phones and PDAs (Personal DigitalAssistants).

Description of the Related Art

In recent years, highly functional products, such as a smart TV as a TVwith a personal computer function and a 4K TV as a TV with four timeshigher resolution than a full high-definition TV, have been attractingattention. As for smart TVs, there has been a tendency towards moremultifunctional models such as ones which incorporate an image pickupdevice capable of taking a high resolution image and can transmit theimage through a communication network, in addition to the highfunctionality. Also, due to its high resolution, a 4K TV can reproducean image which is so realistic as if the object were there. Theseproducts are expected to provide a wider range of functions than before:for example, a security function combined with a high-accuracy facerecognition function and a moving body detection function, a petmonitoring function, and a function of editing an image captured byimage processing technology in various ways. If these products have anability to take higher resolution images or moving images, they areexpected to become products which increase the satisfaction of thegeneral consumers. On the other hand, recently introduced into themarket are smart phones which use an image sensor with a resolution ofmore than 40 megapixels to provide a professional quality digital camerafunction. Therefore, there is a growing demand for higher cameraperformance for these products.

However, in the conventional techniques, it is difficult to provide animaging lens which satisfies the performance requirement of the devicesas mentioned above. For example, the image pickup device used in a smartTV or smart phone with a high resolution imaging function is assumed toadopt a relatively large image sensor suitable for high resolutionimages. In that case, since a larger image sensor is used, there arisesthe following problem: the optical system should be larger, so it isdifficult to correct various aberrations and it is impossible tomaintain the high optical performance achieved so far with aconventional smaller image sensor. In addition, in the case of amonitoring camera, the following problem may arise: the camera isrequired to use a wide-field of view imaging lens and when the lens isdesigned to provide a wide field of view, correction of aberrations maybe very difficult particularly in the peripheral area regardless ofimage sensor size and it may be impossible to deliver satisfactoryoptical performance.

Furthermore, when an imaging lens is used in an image pickup device withan autofocus function which is recently popular, high opticalperformance must be ensured in both imaging of an object at infinity andimaging of an object at close range, but this is very difficultparticularly when the image sensor in use is large. In addition, formobile terminals including smart phones, the imaging lenses must bealways compact enough to meet the product design need.

As an imaging lens built in an apparatus with an image pickup device,the imaging lens described in JP-A-2010-262270 (Patent Document 1) orthe imaging lens described in JP-A-2012-155223 (Patent Document 2) isknown.

Patent Document 1 discloses an imaging lens which includes, in orderfrom an object side, a first lens with positive refractive power havinga convex shape on the object-side surface near an optical axis, a secondlens with negative refractive power, a third lens with positiverefractive power having a concave shape on an image-side surface nearthe optical axis, a fourth lens with positive refractive power having aconvex shape on the image-side surface near the optical axis, and afifth lens with negative refractive power near the optical axis. Theimaging lens described in Patent Document 1 includes five constituentlenses (elements), each of which is optimized to deliver highperformance.

Patent Document 2 discloses an imaging lens which includes, in orderfrom an object side, a first lens group with positive refractive power,a second lens group with negative refractive power, a third lens groupwith positive refractive power, a fourth lens group with negativerefractive power, a fifth lens group with positive refractive power, anda sixth lens group with negative refractive power. In the imaging lensdescribed in Patent Document 2, the lens configuration of the opticalsystem is concentric with an aperture stop so as to suppress astigmatismand coma aberrations and achieve a wider field of view.

In the imaging lens described in Patent Document 1, five constituentlenses are used for higher performance and the lens system provides arelatively wide field of view with a half field of view of about 38degrees. However, its ability to correct aberrations with the fiveconstituent lenses is limited and insufficient to respond the recentdemand for higher resolution.

According to the use of six lens groups, the imaging lens described inPatent Document 2 provides a relatively wide field of view and cancorrect aberrations properly. However, in imaging of an object atinfinity and imaging of an object at close range, a specific lens groupmust be moved in the optical axis direction for focusing, so there is aproblem that the structure is complicated. Also, if the lensconfiguration described in Patent Document 2 is employed to provide awide field of view, correction of aberrations will be difficultparticularly in the peripheral area and high optical performance cannotbe delivered.

As stated above, in the conventional techniques, it is difficult toprovide a compact imaging lens which can take a high resolution image asdemanded in recent years with a wide field of view and delivers highperformance in both imaging of an object at infinity and imaging of anobject at close range.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problem and anobject thereof is to provide a compact imaging lens which delivershigher optical performance than existing imaging lenses, when it is usednot only in a conventional small image sensor but also in a large imagesensor, and can correct various aberrations properly in both imaging ofan object at infinity and imaging of an object at close range eventhough it provides a wide field of view.

A “compact” imaging lens here means an imaging lens in which the ratioof total track length TTL to the length (2ih) of the diagonal of theeffective image plane of the image sensor, that is, TTL/2ih is 1.0 orless. “Total track length” means the distance from the object-sidesurface of an optical element nearest to an object to the image plane onthe optical axis in an optical system.

According to one aspect of the present invention, there is provided animaging lens in which constituent lenses are arranged in the followingorder from an object side to an image side: a first lens with positiverefractive power, a second lens with positive or negative refractivepower, a third lens with negative refractive power, a fourth lens withpositive or negative refractive power as a double-sided aspheric lens, ameniscus fifth lens having a convex surface on the image side, a sixthlens with positive or negative refractive power as a double-sidedaspheric lens, and a seventh lens with negative refractive power. In theimaging lens, an air gap is provided between constituent lenses.

In the above imaging lens, the first lens and the second lens haveadequate refractive power so that spherical aberrations are suppressedand the total track length is short. The third lens with negativerefractive power corrects spherical aberrations and chromaticaberrations properly. The fourth lens, a double-sided aspheric lenscorrects axial chromatic aberrations and high-order sphericalaberrations and suppresses coma aberrations. The meniscus fifth lens,which has a convex surface on the image side, guides off-axial lightrays to the sixth lens while keeping the refraction angles of the rayssmall and mainly corrects astigmatism and field curvature properly. Thesixth lens, a double-sided aspheric lens with positive or negativerefractive power, corrects field curvature and distortion properly inthe peripheral area of the image and also controls the angle of a chiefray incident on the image sensor properly. The seventh lens, locatednearest to the image plane, has negative refractive power, making theimaging lens nearly a telephoto lens.

Regarding all the constituent lenses of the imaging lens according tothe present invention, an air gap is provided between lenses. Each lenssurface can be made aspheric as needed in order to correct aberrationsproperly. If a cemented lens is used, the spherical cemented surface isusually made of glass material but a glass cemented lens is hard tomanufacture and not suitable for mass production. In the presentinvention, all the lenses are made of plastic material and many of thelens surfaces are aspheric as needed to realize a high-performancelow-cost optical system suitable for mass production.

Preferably, in the imaging lens according to the present invention, thefirst lens is a lens with positive refractive power having a convexsurface on the object side, the second lens is a lens with positive ornegative refractive power having a convex surface on the image side, andat least one of the facing surfaces of the first lens and the secondlens is a concave surface. This combination of lens surfaces suppressesspherical aberrations and is also useful in correcting field curvature.More preferably, the relation of r1<|r2| holds, where r1 denotes thecurvature radius of the object-side surface of the first lens and r2denotes the curvature radius of the image-side surface of the firstlens.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (1) below:

0<f12  (1)

-   -   where    -   f12: composite focal length of the first lens and the second        lens

The conditional expression (1) means that the composite focal length ofthe first lens and the second lens is a positive value. When thecomposite refractive power of these two lenses has a positive value, thetotal track length is shortened.

In the imaging lens according to the present invention, the third lensis a lens with negative refractive power which has a concave surface onthe image side near an optical axis and corrects spherical aberrationsand axial chromatic aberrations properly. Preferably, in order to makeit easy to correct off-axial aberrations, both the surfaces of the thirdlens are aspheric. If the third lens has a meniscus shape having aconvex surface on the object side near the optical axis, sphericalaberrations and axial chromatic aberrations can be corrected moreproperly. Furthermore, if the aspheric image-side surface of the thirdlens is designed so that its negative refractive power is weaker as thedistance from the optical axis is larger, it prevents light rays fromjumping in the peripheral portion and can correct various off-axialaberrations properly.

Preferably, in the imaging lens according to the present invention, thefourth lens is a biconvex lens having a convex surface on the objectside near the optical axis or a meniscus lens having a convex surface onthe object side near the optical axis.

The fourth lens plays an important role in suppressing high-orderspherical aberrations or coma aberrations which occur on the first lensand the second lens. The convex object-side surface of the fourth lensshould be an aspheric surface which has a relatively large curvatureradius to reduce change in the amount of sag so that the aberrations asmentioned above are corrected properly. More specifically, it isdesirable that the curvature radius of the fourth lens should be 70% ofthe focal length of the overall optical system or more.

Preferably, in the imaging lens according to the present invention, theimage-side surface of the sixth lens has an aspheric shape in which theportion near the optical axis has a concave shape on the image side andthe concave shape changes to a convex shape in the peripheral portiondistant from the optical axis.

When the image-side surface of the sixth lens has an aspheric shape inwhich the portion near the optical axis has a concave shape and theconcave shape changes to a convex shape in the peripheral portion, fieldcurvature and distortion can be corrected properly. In addition, due tothis aspheric surface, the angle of a chief ray incident on the imagesensor can be controlled properly. If the sixth lens is a meniscus lenshaving a convex surface on the object side near the optical axis,preferably the object-side surface of the sixth lens has an asphericshape in which the peripheral portion of the object-side surface isconcave. When this shape is adopted, it is easy to control the angle ofa chief ray and ensure that the performance in imaging of an object atinfinity is equivalent to the performance in imaging of an object atclose range.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (2) below:

0.6<f12/f<1.3  (2)

-   -   where    -   f12: composite focal length of the first lens and the second        lens    -   f: focal length of the overall optical system of the imaging        lens

The conditional expression (2) defines an adequate range for the ratioof the composite focal length of the first lens and the second lens tothe focal length of the overall optical system of the imaging lens.

If the value is above the upper limit of the conditional expression (2),the positive composite refractive power of the first lens and the secondlens would be too weak, making it difficult to shorten the total tracklength. On the other hand, if the value is below the lower limit of theconditional expression (2), the positive composite refractive power ofthe first lens and the second lens would be too strong, undesirablyresulting in an increase in the amount of spherical aberration.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (3) below:

−2.2<f3/f<−1.0  (3)

-   -   where    -   f3: focal length of the third lens    -   f: focal length of the overall optical system of the imaging        lens

The conditional expression (3) defines an adequate range for the ratioof the focal length of the third lens to the focal length of the overalloptical system of the imaging lens and indicates a condition to correctchromatic aberrations properly.

If the value is above the upper limit of the conditional expression (3),the negative refractive power of the third lens would be too strong,making it difficult to shorten the total track length. On the otherhand, if the value is below the lower limit of the conditionalexpression (3), the negative refractive power of the third lens would betoo weak, making it difficult to correct chromatic aberrations properly.If the value falls within the range defined by the conditionalexpression (3), a compact optical system which can correct chromaticaberrations properly can be obtained.

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (4) below:

0.6<f45/f<2.2  (4)

-   -   where    -   f45: composite focal length of the fourth lens and the fifth        lens    -   f: focal length of the overall optical system of the imaging        lens

The conditional expression (4) defines an adequate range for the ratioof the composite focal length of the fourth lens and the fifth lens tothe focal length of the overall optical system of the imaging lens andindicates a condition to correct various aberrations properly.

If the value is above the upper limit of the conditional expression (4),the composite refractive power of the fourth lens and the fifth lenswould weaken, making it difficult to correct axial chromaticaberrations. On the other hand, if the value is below the lower limit ofthe conditional expression (4), the composite refractive power of thefourth lens and the fifth lens would be too strong, making it difficultto correct coma aberrations and field curvature.

A more preferable form of the conditional expression (4) is aconditional expression (4a) below:

0.7<f45/f<2.0  (4a)

-   -   where    -   f45: composite focal length of the fourth lens and the fifth        lens    -   f: focal length of the overall optical system of the imaging        lens

Preferably, the imaging lens according to the present inventionsatisfies a conditional expression (5) below:

−2.0<f67/f<−0.6  (5)

-   -   where    -   f67: composite focal length of the sixth lens and the seventh        lens    -   f: focal length of the overall optical system of the imaging        lens

The conditional expression (5) defines an adequate range for the ratioof the composite focal length of the sixth lens and the seventh lens tothe focal length of the overall optical system of the imaging lens andindicates a condition to correct various aberrations properly.

If the value is above the upper limit of the conditional expression (5),the composite refractive power of the sixth lens and the seventh lenswould be too strong, making it difficult to correct distortion and fieldcurvature. On the other hand, if the value is below the lower limit, thecomposite refractive power of the sixth lens and the seventh lens wouldweaken, making it difficult to correct axial chromatic aberrations.

Preferably, the imaging lens according to the present inventionsatisfies conditional expressions (6) to (8) below:

50<νd1<70  (6)

50<νd2<70  (7)

20<νd3<30  (8)

-   -   where    -   νd1: Abbe number of the first lens at d-ray    -   νd2: Abbe number of the second lens at d-ray    -   νd3: Abbe number of the third lens at d-ray

The conditional expressions (6) to (8) define adequate ranges for theAbbe numbers of the first to third lenses respectively. When alow-dispersion material is used for the first lens and the second lensand a high-dispersion material is used for the third lens, chromaticaberrations can be corrected properly.

In the imaging lens according to the present invention, the seventh lensis a double-sided aspheric lens with negative refractive power. Sincethe seventh lens, located nearest to the image plane, has negativerefractive power, the imaging lens nearly functions as a telephoto lensso that the total track length is short and it is easy to ensure anadequate back focus. The seventh lens has only to provide negativerefractive power near the optical axis. In other words, the seventh lensmay be any of the following three types: a lens having a biconcave shapenear the optical axis, a meniscus lens having a concave surface on theimage side near the optical axis, and a meniscus lens having a convexsurface on the image side near the optical axis. In particular, if abiconcave lens having a concave surface on the image side near theoptical axis or a meniscus lens having a concave surface on the imageside near the optical axis is adopted, it is preferable that the concaveshape of the aspheric image-side surface near the optical axis shouldchange to a convex shape in its peripheral portion. Such surface shapeis more effective in correcting mainly distortion and field curvatureand in controlling the angle of rays incident on the image sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the general configuration of animaging lens according to Example 1;

FIG. 2 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 1 in which the object is at infinity;

FIG. 3 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 1 in which the distance of the objectis 150 mm;

FIG. 4 is a schematic view showing the general configuration of animaging lens according to Example 2;

FIG. 5 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 2 in which the object is at infinity;

FIG. 6 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 2 in which the distance of the objectis 150 mm;

FIG. 7 is a schematic view showing the general configuration of animaging lens according to Example 3;

FIG. 8 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 3 in which the object is at infinity;

FIG. 9 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 3 in which the distance of the objectis 150 mm;

FIG. 10 is a schematic view showing the general configuration of animaging lens according to Example 4;

FIG. 11 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 4 in which the object is at infinity;

FIG. 12 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 4 in which the distance of the objectis 150 mm;

FIG. 13 is a schematic view showing the general configuration of animaging lens according to Example 5;

FIG. 14 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 5 in which the object is at infinity;

FIG. 15 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 5 in which the distance of the objectis 150 mm;

FIG. 16 is a schematic view showing the general configuration of animaging lens according to Example 6;

FIG. 17 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 6 in which the object is at infinity;

FIG. 18 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 6 in which the distance of the objectis 150 mm;

FIG. 19 is a schematic view showing the general configuration of animaging lens according to Example 7;

FIG. 20 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 7 in which the object is at infinity;

FIG. 21 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 7 in which the distance of the objectis 150 mm;

FIG. 22 is a schematic view showing the general configuration of animaging lens according to Example 8;

FIG. 23 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 8 in which the object is at infinity;

FIG. 24 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 8 in which the distance of the objectis 150 mm;

FIG. 25 is a schematic view showing the general configuration of animaging lens according to Example 9;

FIG. 26 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 9 in which the object is at infinity;

FIG. 27 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 9 in which the distance of the objectis 150 mm;

FIG. 28 is a schematic view showing the general configuration of animaging lens according to Example 10;

FIG. 29 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 10 in which the object is at infinity;and

FIG. 30 shows spherical aberration, astigmatism, and distortion of theimaging lens according to Example 10 in which the distance of the objectis 150 mm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the preferred embodiment of the present invention will bedescribed in detail referring to the accompanying drawings.

FIGS. 1, 4, 7, 10, 13, 16, 19, 22, 25, and 28 are schematic viewsshowing the general configurations of the imaging lenses according toExamples 1 to 10 of the present embodiment, respectively. Since allthese Examples have the same basic configuration, a general explanationof an imaging lens according to the present embodiment is mainly givenbelow referring to the schematic view of Example 1.

As shown in FIG. 1, in the imaging lens according to the presentembodiment, the elements are arranged in the following order from anobject side to an image side: a first lens L1 with positive refractivepower, a second lens L2 with positive refractive power, a third lens L3with negative refractive power, a fourth lens L4 with positiverefractive power as a double-sided aspheric lens, a fifth lens L5 as ameniscus lens having a convex surface on the image side, a sixth lens L6with negative refractive power as a double-sided aspheric lens, and aseventh lens L7 with negative refractive power, in which an air gap isprovided between constituent lenses. An aperture stop ST is locatedbetween the first lens L1 and the second lens L2, and a filter IR islocated between the seventh lens L7 and an image plane IMG. This filterIR is omissible.

The first lens L1 is a meniscus lens having a convex surface on theobject side. The second lens L2 is a biconvex lens having a convexsurface on the image side. The composite refractive power of these twolenses is designed to have an adequate positive value so that the totaltrack length is short. At least one of the facing surfaces of the firstlens L1 and the second lens L2 is concave so that spherical aberrationsare suppressed. Therefore, the shape of the first lens L1 is not limitedto a meniscus shape having a convex surface on the object side and forexample, it may be a biconvex lens as seen in Examples 5, 7 and 10 whichwill be described later. In that case, however, the object-side surfaceof the second lens L2 must be concave.

The third lens L3 is a meniscus lens having a concave surface on theimage side near an optical axis X, in which aspheric surfaces are formedon both sides to correct spherical aberrations and axial chromaticaberrations which are generated on the first lens L1 and the second lensL2. The aspheric surface formed on the image side of the third lens L3is so shaped that the negative refractive power weakens as the distancefrom the optical axis X increases. This prevents off-axial light raysemitted from the third lens L3 from jumping excessively. Consequently,it is also effective in correcting off-axial aberrations properly.

The fourth lens L4 is a double-sided aspheric lens with positiverefractive power which has a biconvex shape near the optical axis X. Thecurvature radii of the object-side surface and the image-side surface ofthe fourth lens L4 are both not less than 70% of the focal length of theoverall optical system of the imaging lens. The aspheric shape isdesigned to reduce change in the amount of sag. Such shape is effectivein correcting axial chromatic aberrations and high-order sphericalaberrations and suppressing coma aberrations. The fourth lens L4 is notlimited to a lens having a biconvex shape near the optical axis X andfor example, it may be a meniscus lens with negative refractive powerhaving a convex surface on the object side near the optical axis X asseen in Example 7 or a meniscus lens with positive refractive powerhaving a convex surface on the object side near the optical axis X asseen in Example 8.

The fifth lens L5 is a meniscus lens with weak positive refractive powerhaving a convex surface on the image side and guides off-axial lightrays to the sixth lens L6 at a small refraction angle and mainlycorrects astigmatism and field curvature properly. The fifth lens L5 isnot limited to a lens with positive refractive power. For example, thefifth lens L5 in Example 9 is a meniscus lens with negative refractivepower having a concave surface on the image side.

The sixth lens L6 is a meniscus lens having a concave surface on theimage side near the optical axis x in which the peripheral portion ofthe aspheric image-side surface is convex. Such aspheric shape iseffective in properly correcting field curvature and distortion in theperipheral area of the image and controlling the angle of a chief rayincident on the image sensor adequately. Also, it is desirable that thesixth lens L6 should have weak negative refractive power near theoptical axis X to reduce the influence of the refractive power on theoverall optical system of the imaging lens and be mainly used forcorrection of aberrations, but it may have weak positive refractivepower. For example, the sixth lens L6 in Example 9 has weak positiverefractive power.

The seventh lens L7 is a double-sided aspheric lens with negativerefractive power near the optical axis X. Since the seventh lens L7,located nearest to the image plane, has negative refractive power, anadequate back focus is ensured. The seventh lens L7 has only to providenegative refractive power near the optical axis X; for example, inExamples 1, 2, 5, 7, 8 and 9, the seventh lens L7 has a biconcave shapenear the optical axis X, in Examples 3 and 4, it is a meniscus lenshaving a concave image-side surface near the optical axis X, and inExamples 6 and 10, it is a meniscus lens having a convex image-sidesurface near the optical axis X. Particularly when the image-sidesurface is concave near the optical axis X, if the seventh lens L7 isdesigned so that the concave shape on the aspheric image-side surfacechanges to a convex shape in its peripheral portion, it is moreeffective in mainly correcting distortion and field curvature andcontrolling the angle of rays incident on the image sensor.

The imaging lens according to the present invention satisfiesconditional expressions (1) to (8) below:

0<f12  (1)

0.6<f12/f<1.3  (2)

−2.2<f3/f<−1.0  (3)

0.6<f45/f<2.2  (4)

−2.0<f67/f<−0.6  (5)

50<νd1<70  (6)

50<νd2<70  (7)

20<νd3<30  (8)

-   -   where    -   f: focal length of the overall optical system of the imaging        lens    -   f3: focal length of the third lens L3    -   f12: composite focal length of the first lens L1 and the second        lens L2    -   f45: composite focal length of the fourth lens L4 and the fifth        lens L5    -   f67: composite focal length of the sixth lens L6 and the seventh        lens L7    -   νd1: Abbe number of the first lens L1 at d-ray    -   νd2: Abbe number of the second lens L2 at d-ray    -   νd3: Abbe number of the third lens L3 at d-ray

Since the conditional expression (1) is satisfied, the compositerefractive power of the first lens L1 and the second lens L2 has apositive value, leading to a shorter total track length.

Since the conditional expression (2) is satisfied, the ratio of thecomposite focal length of the first lens L1 and the second lens L2 tothe focal length of the overall optical system of the imaging lens fallswithin the adequate range so that the total track length is shortenedand spherical aberrations are corrected properly.

Since the conditional expression (3) is satisfied, the ratio of thenegative focal length of the third lens L3 to the focal length of theoverall optical system of the imaging lens falls within the adequaterange so that the total track length is shortened and chromaticaberrations are corrected properly.

Since the conditional expression (4) is satisfied, the ratio of thepositive composite focal length of the fourth lens L4 and the fifth lensL5 to the focal length of the overall optical system of the imaging lensfalls within the adequate range so that axial chromatic aberrations,coma aberrations, and field curvature are corrected properly.

Since the conditional expression (5) is satisfied, the ratio of thenegative composite focal length of the sixth lens L6 and the seventhlens L7 to the focal length of the overall optical system of the imaginglens falls within the adequate range so that distortion, fieldcurvature, and axial chromatic aberrations are corrected properly.

Since the conditional expressions (6) to (8) are satisfied, chromaticaberrations are corrected properly.

In this embodiment, all the lens surfaces are aspheric. The asphericshapes of these lens surfaces are expressed by the following Equation 1,where Z denotes an axis in the optical axis direction, H denotes aheight perpendicular to the optical axis, k denotes a conic constant,and A4, A6, A8, A10, A12, A14, and A16 denote aspheric surfacecoefficients.

$\begin{matrix}{Z = {\frac{\frac{H^{2}}{R}}{1 + \sqrt{1 - {\left( {k + 1} \right)\frac{H^{2}}{R}}}} + {A_{4}H^{4}} + {A_{6}H^{6}} + {A_{8}H^{8}} + {A_{10}H^{10}} + {A_{12}H^{12}} + {A_{14}H^{14}} + {A_{16}H^{16}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Next, the imaging lenses according to Examples of the present embodimentwill be explained. In each Example, f denotes the focal length of theoverall optical system of the imaging lens, Fno denotes an F-number, ωdenotes a half field of view, ih denotes a maximum image height, and TTLdenotes a total track length. i denotes a surface number counted fromthe object side, r denotes a curvature radius, d denotes the distancebetween lens surfaces on the optical axis (surface distance), Nd denotesa refractive index with respect to d-ray (reference wavelength), and νddenotes an Abbe number with respect to d-ray. As for aspheric surfaces,an asterisk (*) after surface number i indicates that the surfaceconcerned is an aspheric surface. Total track length TTL indicated hereis a distance (total track length) in which the filter IR locatedbetween the seventh lens L7 and the image plane IMG is removed.

Example 1

The basic lens data of Example 1 is shown below in Table 1.

TABLE 1 Example 1 in mm f = 7.51 Fno = 2.6 ω(°) = 38.2 ih = 5.99 TTL =9.88 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 3.924 0.468 1.5438 55.57  2* 7.251 0.256  3 (Stop) Infinity −0.060 4* 8.010 0.485 1.5438 55.57  5* −48.281 0.018  6* 4.641 0.422 1.634923.97  7* 2.652 0.353  8* 11.635 0.680 1.5438 55.57  9* −7.596 0.921 10*−2.398 1.584 1.5438 55.57 11* −2.515 0.019 12* 6.401 1.287 1.5438 55.5713* 5.113 0.955 14* −85.8141 1.051 1.6142 25.58 15* 6.9862 0.300 16Infinity 0.210 1.5168 64.20 17 Infinity 0.985 Image Plane InfinityConstituent Lens Data Lens Start Surface Focal Length 1 1 14.98 2 412.67 3 6 −10.62 4 8 8.56 5 10 25.17 6 12 −72.11 7 14 −10.47 LensComposite Focal Length First Lens-Second Lens 7.09 Fourth Lens-FifthLens 7.96 Sixth Lens-Seventh Lens −9.56 Aspheric Surface Data 1stSurface 2nd Surface 4th Surface 5th Surface 6th Surface 7th Surface 8thSurface k 0.000E+00 0.000E+00 0.000E+00 0.000E+00 −2.298E+01  −6.498E+00   0.000E+00 A4 −3.681E−03   −5.084E−03   3.301E−03 3.772E−03−6.425E−03   −2.244E−03   1.934E−03 A6 −1.125E−03   −3.401E−04  −3.268E−04   −2.025E−03   −9.035E−04   7.244E−04 8.028E−04 A8−2.547E−04   0.000E+00 0.000E+00 −1.292E−03   −3.708E−05   1.491E−040.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 3.580E−04 1.654E−04−4.066E−05   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+00 0.000E+000.000E+00 2.608E−05 0.000E+00 A14 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 −3.572E−06   0.000E+00 A16 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface 10thSurface 11th Surface 12th Surface 13th Surface 14th Surface 15th Surfacek 0.000E+00 0.000E+00 −9.155E−01   0.000E+00 0.000E+00 0.000E+000.000E+00 A4 6.539E−03 1.499E−02 −3.441E−04   −1.147E−02   −8.992E−03  −7.734E−03   −1.090E−02   A6 2.180E−03 −2.367E−05   1.650E−04 1.505E−04−2.031E−05   2.167E−04 4.282E−04 A8 0.000E+00 1.447E−04 −5.051E−05  −1.898E−05   6.071E−06 0.000E+00 −5.608E−06   A10 0.000E+00 0.000E+000.000E+00 0.000E+00 −3.533E−07   0.000E+00 −2.129E−07   A12 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 5.359E−09 A140.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 1.491E−10A16 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00−4.371E−12  

As shown in Table 11, the imaging lens according to Example 1 satisfiesall the conditional expressions (1) to (8).

FIG. 2 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens according to Example 1 in which the object is atinfinity. The spherical aberration graph shows the amount of aberrationat wavelengths of g-ray (436 nm), F-ray (486 nm), e-ray (546 nm), d-ray(588 nm), and C-ray (656 nm). The astigmatism graph shows the amount ofaberration on sagittal image surface S and the amount of aberration ontangential image surface T at d-ray (the same is true for FIGS. 5, 8,11, 14, 17, 20, 23, 26, and 29). As shown in FIG. 2, various aberrationsare properly corrected. FIG. 3 shows spherical aberration (mm),astigmatism (mm), and distortion (%) of the imaging lens according toExample 1 in which the entire imaging lens is extended for autofocusingand the distance of the object is 150 mm. The spherical aberration graphshows the amount of aberration at wavelengths of g-ray (436 nm), F-ray(486 nm), e-ray (546 nm), d-ray (588 nm), and C-ray (656 nm). Theastigmatism graph shows the amount of aberration on sagittal imagesurface S and the amount of aberration on tangential image surface T atd-ray (the same is true for FIGS. 6, 9, 12, 15, 18, 21, 24, 27, and 30).As shown in FIG. 3, various aberrations are properly corrected even inimaging of an object at close range.

The imaging lens provides a wide field of view of nearly 80 degrees andrelatively high brightness with an F-value of 2.6. The ratio of totaltrack length TTL to maximum image height ih (TTL/2ih) is 0.82, so itoffers a compact design though it uses seven constituent lenses.

Example 2

The basic lens data of Example 2 is shown below in Table 2.

TABLE 2 Example 2 in mm f = 7.47 Fno = 2.6 ω(°) = 38.3 ih = 5.99 TTL =9.65 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 3.712 0.48   1.543812  55.5699  2* 6.560 0.280  3 (Stop) Infinity−0.080    4* 8.676 0.510 1.5438 55.57  5* −28.537    0.029  6* 5.9440.564 1.6349 23.97  7* 3.045 0.343  8* 12.794  0.681 1.5438 55.57  9*−7.984   0.998 10* −2.392   1.186 1.5438 55.57 11* −2.386   0.021 12*7.769 1.476 1.5438 55.57 13* 5.147 0.864 14* −62.288    1.105 1.614225.58 15* 7.497 0.295 16 Infinity 0.210 1.5168 64.20 17 Infinity 0.750Image Plane Infinity Constituent Lens Data Lens Start Surface FocalLength 1 1 14.84  2 4 12.29  3 6 −10.63    4 8 9.15 5 10  24.78  6 12 −34.98    7 14  −10.83    Lens Composite Focal Length First Lens-SecondLens 6.97 Fourth Lens-Fifth Lens 7.98 Sixth Lens-Seventh Lens −8.43 Aspheric Surface Data 1st Surface 2nd Surface 4th Surface 5th Surface6th Surface 7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+000.000E+00 −2.947E+01   −6.483E+00   0.000E+00 A4 −5.802E−03  −7.443E−03   4.772E−03 2.916E−03 −7.007E−03   −1.314E−03   5.325E−04 A6−6.602E−04   4.272E−04 −8.917E−04   −1.288E−03   −4.097E−05   1.491E−038.206E−04 A8 −1.594E−04   0.000E+00 0.000E+00 −1.301E−03 1.627E−041.157E−04 0.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 4.056E−041.594E−04 −4.045E−05   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 2.816E−05 0.000E+00 A14 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 −3.481E−06   0.000E+00 A16 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface10th Surface 11th Surface 12th Surface 13th Surface 14th Surface 15thSurface k 0.000E+00 0.000E+00 −1.009E+00   0.000E+00 0.000E+00 0.000E+000.000E+00 A4 3.947E−03 1.560E−02 −4.529E−05   −1.290E−02   −1.005E−02  −5.997E−03   −9.601E−03   A6 1.154E−03 −5.492E−04   1.183E−04 3.363E−041.892E−04 1.359E−04 3.703E−04 A8 0.000E+00 5.607E−05 −1.005E−04  −3.456E−05   −5.343E−06   0.000E+00 −5.393E−06   A10 0.000E+00 0.000E+000.000E+00 0.000E+00 −1.581E−07   0.000E+00 −1.896E−07   A12 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 5.631E−09 A140.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 1.437E−10A16 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00−4.749E−12  

As shown in Table 11, the imaging lens according to Example 2 satisfiesall the conditional expressions (1) to (8).

FIG. 5 shows various aberrations of the imaging lens according toExample 2 in which the object is at infinity, and FIG. 6 shows variousaberrations of the imaging lens according to Example 2 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 5 and 6, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andrelatively high brightness with an F-value of 2.6. The ratio of totaltrack length TTL to maximum image height ih (TTL/2ih) is 0.80, so itoffers a compact design though it uses seven constituent lenses.

Example 3

The basic lens data of Example 3 is shown below in Table 3.

TABLE 3 Example 3 in mm f = 7.51 Fno = 2.6 ω(°) = 37.7 ih = 5.99 TTL =9.93 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 4.135 0.468 1.5438 55.57  2* 8.081 0.237  3 (Stop) Infinity 0.000 4* 9.482 0.504 1.5438 55.57  5* −22.482    0.018  6* 5.240 0.531 1.634923.97  7* 2.805 0.385  8* 13.532  0.577 1.5438 55.57  9* −8.307   0.93110* −2.499   1.525 1.5438 55.57 11* −2.502   0.020 12* 5.829 1.2561.5438 55.57 13* 4.686 0.852 14* 42.9885 1.003 1.6142 25.58 15* 6.0760.300 16 Infinity 0.210 1.5168 64.20 17 Infinity 1.175 Image PlaneInfinity Constituent Lens Data Lens Start Surface Focal Length 1 114.94  2 4 12.33  3 6 −10.38    4 8 9.55 5 10  21.52  6 12  −71.69    714  −11.64    Lens Composite Focal Length First Lens-Second Lens 7.00Fourth Lens-Fifth Lens 8.10 Sixth Lens-Seventh Lens −10.50    AsphericSurface Data 1st Surface 2nd Surface 4th Surface 5th Surface 6th Surface7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+00 0.000E+00−2.524E+01   −6.329E+00   0.000E+00 A4 −4.543E−03   −5.877E−03  3.955E−03 3.611E−03 −6.488E−03   −2.996E−03   1.251E−03 A6 −8.319E−04  −1.569E−04   −7.688E−04   −2.045E−03   −9.311E−04   3.512E−04 9.098E−04A8 −2.061E−04   0.000E+00 0.000E+00 −1.205E−03   −1.790E−04   1.065E−040.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 3.101E−04 1.416E−04−6.606E−05   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+00 0.000E+000.000E+00 2.286E−05 0.000E+00 A14 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 −3.032E−06   0.000E+00 A16 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface 10thSurface 11th Surface 12th Surface 13th Surface 14th Surface 15th Surfacek 0.000E+00 0.000E+00 −9.535E−01   0.000E+00 0.000E+00 0.000E+000.000E+00 A4 7.155E−03 1.606E−02 2.462E−05 −1.209E−02   −9.586E−03  −7.462E−03   −1.150E−02   A6 2.436E−03 −1.064E−04   8.496E−05 1.609E−041.332E−06 2.137E−04 4.407E−04 A8 0.000E+00 2.067E−04 0.000E+00 0.000E+008.035E−06 0.000E+00 −6.069E−06   A10 0.000E+00 0.000E+00 0.000E+000.000E+00 −4.396E−07   0.000E+00 −1.892E−07   A12 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 5.041E−09 A14 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 1.425E−10 A160.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 −4.420E−12  

As shown in Table 11, the imaging lens according to Example 3 satisfiesall the conditional expressions (1) to (8).

FIG. 8 shows various aberrations of the imaging lens according toExample 3 in which the object is at infinity, and FIG. 9 shows variousaberrations of the imaging lens according to Example 3 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 8 and 9, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andrelatively high brightness with an F-value of 2.6. The ratio of totaltrack length TTL to maximum image height ih (TTL/2ih) is 0.83, so itoffers a compact design though it uses seven constituent lenses.

Example 4

The basic lens data of Example 4 is shown below in Table 4.

TABLE 4 Example 4 in mm f = 7.61 Fno = 2.6 ω(°) = 37.7 ih = 5.99 TTL =9.51 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 3.672 0.468 1.5438 55.57  2* 7.066 0.237  3 (Stop) Infinity 0.000 4* 16.245  0.564 1.5438 55.57  5* −10.566    0.027  6* 5.401 0.6171.6349 23.97  7* 2.789 0.272  8* 11.800  0.629 1.5438 55.57  9* −7.986  0.893 10* −2.371   0.863 1.5438 55.57 11* −2.046   0.020 12* −100.000   1.500 1.5438 55.57 13* 6.099 0.467 14* 21.2943 1.432 1.6142 25.58 15* 6.59893 0.300 16 Infinity 0.210 1.5168 64.20 17 Infinity 1.073 ImagePlane Infinity Constituent Lens Data Lens Start Surface Focal Length 1 113.41  2 4 11.86  3 6 −10.00    4 8 8.86 5 10  14.19  6 12  −10.52    714  −16.17    Lens Composite Focal Length First Lens-Second Lens 6.57Fourth Lens-Fifth Lens 6.32 Sixth Lens-Seventh Lens −5.96   AsphericSurface Data 1st Surface 2nd Surface 4th Surface 5th Surface 6th Surface7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+00 0.000E+000.000E+00 −2.781E+01   −6.245E+00   A4 −7.243E−03   −8.036E−03  6.777E−03 4.089E−03 −8.671E−03 −3.634E−03   1.804E−03 A6 −1.196E−03  4.251E−04 −3.233E−04   −1.658E−03   −1.175E−03   3.845E−04 1.788E−03 A8−2.487E−04   0.000E+00 0.000E+00 −1.412E−03   −1.205E−04   3.638E−040.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 3.585E−04 1.833E−04−1.502E−04   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+00 0.000E+000.000E+00 3.800E−05 0.000E+00 A14 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 −3.187E−06   0.000E+00 A16 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface 10thSurface 11th Surface 12th Surface 13th Surface 14th Surface 15th Surfacek 0.000E+00 0.000E+00 0.000E+00 −8.619E−01   0.000E+00 0.000E+000.000E+00 A4 5.027E−03 1.397E−02 −1.659E−03   −2.042E−02   −1.047E−02  −4.950E−03   −1.021E−02   A6 3.568E−03 6.744E−04 3.830E−05 9.069E−054.616E−05 −6.761E−05   4.330E−04 A8 0.000E+00 2.283E−04 0.000E+000.000E+00 1.050E−05 0.000E+00 −6.954E−06   A10 0.000E+00 0.000E+000.000E+00 0.000E+00 −6.458E−07   0.000E+00 −4.368E−07   A12 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 1.414E−08 A140.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 2.236E−10A16 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00−9.606E−12  

As shown in Table 11, the imaging lens according to Example 4 satisfiesall the conditional expressions (1) to (8).

FIG. 11 shows various aberrations of the imaging lens according toExample 4 in which the object is at infinity, and FIG. 12 shows variousaberrations of the imaging lens according to Example 4 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 11 and 12, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andrelatively high brightness with an F-value of 2.6. The ratio of totaltrack length TTL to maximum image height ih (TTL/2ih) is 0.79, so itoffers a compact design though it uses seven constituent lenses.

Example 5

The basic lens data of Example 5 is shown below in Table 5.

TABLE 5 Example 5 in mm f = 7.468 Fno = 2.6 ω(°) = 38.2 ih = 5.99 TTL =9.60 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 4.438 0.583 1.5438 55.57  2* −81.371    0.078  3 (Stop) Infinity0.181  4* −8.429   0.471 1.5438 55.57  5* −6.404   0.018  6* 4.954 0.4571.6349 23.97  7* 2.639 0.326  8* 7.860 0.608 1.5438 55.57  9* −13.100   1.013 10* −2.514   1.211 1.5438 55.57 11* −2.409   0.018 12* 6.622 1.4011.5438 55.57 13* 4.469 0.998 14* −18.3113   1.067 1.5438 55.57 15* 9.0540.300 16 Infinity 0.210 1.5168 64.20 17 Infinity 0.722 Image PlaneInfinity Constituent Lens Data Lens Start Surface Focal Length 1 1 7.762 4 45.29  3 6 −9.63   4 8 9.13 5 10  20.92  6 12  −32.79    7 14 −10.99    Lens Composite Focal Length First Lens-Second Lens 6.85 FourthLens-Fifth Lens 7.61 Sixth Lens-Seventh Lens −8.42   Aspheric SurfaceData 1st Surface 2nd Surface 4th Surface 5th Surface 6th Surface 7thSurface 8th Surface k 0.000E+00 0.000E+00 0.000E+00 0.000E+00−3.107E+01   −6.796E+00   0.000E+00 A4 −5.673E−03   −6.387E−03  7.637E−03 1.841E−03 −8.302E−03   −1.430E−03   −9.968E−04   A6−1.785E−03   6.113E−04 −1.213E−03   −1.413E−03   −2.961E−04   1.611E−031.488E−03 A8 −1.141E−04   0.000E+00 0.000E+00 −1.383E−03   2.601E−046.243E−05 0.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 3.647E−041.128E−04 −9.977E−05   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 4.021E−05 0.000E+00 A14 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 −3.481E−06   0.000E+00 A16 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface10th Surface 11th Surface 12th Surface 13th Surface 14th Surface 15thSurface k 0.000E+00 0.000E+00 −9.697E−01   0.000E+00 0.000E+00 0.000E+000.000E+00 A4 4.100E−03 1.785E−02 −4.443E−04   −1.662E−02   −1.310E−02  −5.710E−03   −9.278E−03   A6 1.709E−03 −7.718E−04   2.441E−04 4.257E−043.605E−04 1.947E−04 3.010E−04 A8 0.000E+00 5.114E−05 −1.432E−04  −7.566E−05   −1.398E−05   0.000E+00 −3.688E−06   A10 0.000E+00 0.000E+000.000E+00 0.000E+00 −8.723E−09   0.000E+00 −7.926E−08   A12 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 4.322E−09 A140.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 4.944E−11A16 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00−3.757E−12  

As shown in Table 11, the imaging lens according to Example 5 satisfiesall the conditional expressions (1) to (8).

FIG. 14 shows various aberrations of the imaging lens according toExample 5 in which the object is at infinity, and FIG. 15 shows variousaberrations of the imaging lens according to Example 5 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 14 and 15, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andrelatively high brightness with an F-value of 2.6. The ratio of totaltrack length TTL to maximum image height ih (TTL/2ih) is 0.80, so itoffers a compact design though it uses seven constituent lenses.

Example 6

The basic lens data of Example 6 is shown below in Table 6.

TABLE 6 Example 6 in mm f = 7.47 Fno = 2.4 ω(°) = 38.3 ih = 5.99 TTL =9.61 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 4.228 0.485 1.5438 55.57  2* 21.299  0.185  3 (Stop) Infinity 0.071 4* −17.571    0.527 1.5438 55.57  5* −6.745   0.018  6* 4.767 0.4531.6349 23.97  7* 2.643 0.312  8* 9.287 0.552 1.5438 55.57  9* −11.453   1.010 10* −2.332   1.363 1.5438 55.57 11* −2.306   0.020 12* 6.453 1.5001.5438 55.57 13* 4.512 1.210 14*  −6.0891   0.774 1.6142 25.58 15*−95     0.300 16 Infinity 0.210 1.5168 64.20 17 Infinity 0.684 ImagePlane Infinity Constituent Lens Data Lens Start Surface Focal Length 1 19.61 2 4 19.79  3 6 −10.18    4 8 9.52 5 10  19.52  6 12  −37.92    714  −10.63    Lens Composite Focal Length First Lens-Second Lens 6.74Fourth Lens-Fifth Lens 7.82 Sixth Lens-Seventh Lens −8.64   AsphericSurface Data 1st Surface 2nd Surface 4th Surface 5th Surface 6th Surface7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+00 0.000E+00−2.970E+01   −7.426E+00   0.000E+00 A4 −7.587E−03   −8.307E−03  9.881E−03 5.442E−03 −1.009E−02   −4.272E−03   −1.655E−03   A6−2.348E−03   1.567E−03 1.348E−03 −1.394E−03   −3.885E−04   1.278E−031.102E−03 A8 −1.446E−04   0.000E+00 0.000E+00 −1.481E−03   −1.770E−05  2.871E−04 0.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 3.659E−041.067E−04 −1.215E−04   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 2.015E−05 0.000E+00 A14 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 −7.263E−07   0.000E+00 A16 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface10th Surface 11th Surface 12th Surface 13th Surface 14th Surface 15thSurface k 0.000E+00 0.000E+00 −8.168E−01   0.000E+00 0.000E+00 0.000E+000.000E+00 A4 4.557E−03 1.858E−02 −2.357E−03   −1.879E−02   −1.394E−02  −4.410E−05   −5.882E−03   A6 1.515E−03 −1.713E−03   5.729E−04 8.013E−045.864E−04 4.363E−05 2.120E−04 A8 0.000E+00 3.873E−04 −1.264E−04  −8.057E−05   −2.756E−05   0.000E+00 −1.138E−06   A10 0.000E+00 0.000E+000.000E+00 0.000E+00 2.617E−07 0.000E+00 −2.542E−08   A12 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 −5.281E−10   A140.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 2.265E−11A16 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00−1.851E−12  

As shown in Table 11, the imaging lens according to Example 6 satisfiesall the conditional expressions (1) to (8).

FIG. 17 shows various aberrations of the imaging lens according toExample 6 in which the object is at infinity, and FIG. 18 shows variousaberrations of the imaging lens according to Example 6 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 17 and 18, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andhigh brightness with an F-value of 2.4. The ratio of total track lengthTTL to maximum image height ih (TTL/2ih) is 0.80, so it offers a compactdesign though it uses seven constituent lenses.

Example 7

The basic lens data of Example 7 is shown below in Table 7.

TABLE 7 Example 7 in mm f = 7.52 Fno = 2.6 ω(°) = 38.1 ih = 5.99 TTL =9.76 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 5.305 0.526 1.5438 55.57  2* −16.781    0.021  3 (Stop) Infinity0.203  4* −6.885   0.527 1.5438 55.57  5* −4.675   0.018  6* 5.866 0.4091.6349 23.97  7* 3.438 0.378  8* 22.701  0.675 1.6142 25.58  9* 20.000 1.004 10* −3.416   0.973 1.5438 55.57 11* −2.536   0.020 12* 5.741 1.5031.5438 55.57 13* 4.538 1.124 14* −45.2955   1.118 1.6142 25.58 15* 7.7347 0.300 16 Infinity 0.210 1.5168 64.20 17 Infinity 0.820 ImagePlane Infinity Constituent Lens Data Lens Start Surface Focal Length 1 17.48 2 4 24.72  3 6 −14.00    4 8 −302.47    5 10  13.02  6 12 −71.13    7 14  −10.67    Lens Composite Focal Length First Lens-SecondLens 6.01 Fourth Lens-Fifth Lens 13.64  Sixth Lens-Seventh Lens −9.86  Aspheric Surface Data 1st Surface 2nd Surface 4th Surface 5th Surface6th Surface 7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+000.000E+00 −3.056E+01   −7.657E+00   0.000E+00 A4 −9.203E−03  −6.526E−03   9.043E−03 9.874E−05 −8.557E−03   −3.065E−03   −1.207E−03  A6 −2.696E−03   1.268E−04 −1.742E−04   −1.023E−03   −1.214E−03  1.216E−03 2.024E−03 A8 −2.373E−04   0.000E+00 0.000E+00 −1.017E−03  −2.494E−05   1.572E−05 0.000E+00 A10 0.000E+00 0.000E+00 0.000E+002.804E−04 1.964E−04 −1.073E−04   0.000E+00 A12 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 5.115E−05 0.000E+00 A14 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 −3.527E−06   0.000E+00 A160.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+009th Surface 10th Surface 11th Surface 12th Surface 13th Surface 14thSurface 15th Surface k 0.000E+00 0.000E+00 −1.075E+00   0.000E+000.000E+00 0.000E+00 0.000E+00 A4 3.404E−03 1.715E−02 4.304E−04−1.416E−02   −1.210E−02   −6.414E−03   −8.982E−03   A6 8.983E−04−8.771E−04   4.437E−04 5.651E−04 3.585E−04 1.754E−04 2.930E−04 A80.000E+00 6.933E−06 −7.997E−05   −3.859E−05   −1.313E−05   0.000E+00−3.262E−06   A10 0.000E+00 0.000E+00 0.000E+00 0.000E+00 −6.078E−08  0.000E+00 −1.744E−07   A12 0.000E+00 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 5.456E−09 A14 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 1.177E−10 A16 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 −4.877E−12  

As shown in Table 11, the imaging lens according to Example 7 satisfiesall the conditional expressions (1) to (8).

FIG. 20 shows various aberrations of the imaging lens according toExample 7 in which the object is at infinity, and FIG. 21 shows variousaberrations of the imaging lens according to Example 7 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 20 and 21, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andrelatively high brightness with an F-value of 2.6. The ratio of totaltrack length TTL to maximum image height ih (TTL/2ih) is 0.81, so itoffers a compact design though it uses seven constituent lenses.

Example 8

The basic lens data of Example 8 is shown below in Table 8.

TABLE 8 Example 8 in mm f = 7.35 Fno = 2.5 ω(°) = 38.1 ih = 5.99 TTL =9.46 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 4.126 0.488 1.5438 55.57  2* 27.823  0.176  3 (Stop) Infinity 0.128 4* −9.107   0.504 1.5438 55.57  5* −5.481   0.018  6* 4.477 0.3771.6349 23.97  7* 2.596 0.255  8* 5.706 0.494 1.5438 55.57  9* 95.000 1.192 10* −2.340   1.176 1.5438 55.57 11* −2.194   0.018 12* 6.759 1.6001.5438 55.57 13*  4.7209 1.036 14*  −7.3276   0.926 1.6142 25.58 15*69.3383 0.300 16 Infinity 0.210 1.5168 64.20 17 Infinity 0.639 ImagePlane Infinity Constituent Lens Data Lens Start Surface Focal Length 1 18.84 2 4 24.13  3 6 −10.55    4 8 11.14  5 10  16.87  6 12  −39.80    714  −10.74    Lens Composite Focal Length First Lens-Second Lens 6.77Fourth Lens-Fifth Lens 8.07 Sixth Lens-Seventh Lens −8.85   AsphericSurface Data 1st Surface 2nd Surface 4th Surface 5th Surface 6th Surface7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+00 0.000E+00−2.632E+01   −7.472E+00   0.000E+00 A4 −8.517E−03   −9.012E−03  1.127E−02 4.298E−03 −1.117E−02   −3.998E−03   −3.260E−03   A6−2.536E−03   1.390E−03 1.686E−03 −1.531E−03   −6.914E−04   1.248E−037.717E−04 A8 −3.671E−04   0.000E+00 0.000E+00 −1.432E−03   −3.742E−05  3.045E−04 0.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 3.826E−041.584E−04 −1.142E−04   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 2.381E−05 0.000E+00 A14 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 −7.263E−07   0.000E+00 A16 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface10th Surface 11th Surface 12th Surface 13th Surface 14th Surface 15thSurface k 0.000E+00 0.000E+00 −7.896E−01   0.000E+00 0.000E+00 0.000E+000.000E+00 A4 5.630E−03 1.646E−02 −2.760E−03   −1.839E−02   −1.264E−02  4.685E−04 −5.386E−03   A6 5.377E−04 −2.033E−03   4.905E−04 9.492E−045.286E−04 −1.829E−06   1.687E−04 A8 0.000E+00 4.884E−04 −1.012E−04  −8.811E−05   −2.519E−05   0.000E+00 −2.906E−07   A10 0.000E+00 0.000E+000.000E+00 0.000E+00 2.486E−07 0.000E+00 −9.285E−09   A12 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 −1.847E−09   A140.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 1.260E−12A16 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+002.940E−13

As shown in Table 11, the imaging lens according to Example 8 satisfiesall the conditional expressions (1) to (8).

FIG. 23 shows various aberrations of the imaging lens according toExample 8 in which the object is at infinity, and FIG. 24 shows variousaberrations of the imaging lens according to Example 8 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 23 and 24, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andhigh brightness with an F-value of 2.5. The ratio of total track lengthTTL to maximum image height ih (TTL/2ih) is 0.79, so it offers a compactdesign though it uses seven constituent lenses.

Example 9

The basic lens data of Example 9 is shown below in Table 9.

TABLE 9 Example 9 in mm f = 7.47 Fno = 2.6 ω(°) = 38.23 ih = 5.99 TTL =9.79 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 4.789 0.460 1.5438 55.57  2* 16.752  0.160  3 (Stop) Infinity 0.110 4* 95.000  0.520 1.5438 55.57  5* −7.479   0.018  6* 5.133 0.500 1.634923.97  7* 2.770 0.451  8* 26.898  0.725 1.5438 55.57  9* −5.144   0.78310* −2.200   1.444 1.5438 55.57 11* −2.832   0.020 12* 4.504 1.2931.5438 55.57 13*  4.2233 1.299 14* −11.9795   0.927 1.6142 25.58 15*13.4543 0.250 16 Infinity 0.210 1.5168 64.20 17 Infinity 0.687 ImagePlane Infinity Constituent Lens Data Lens Start Surface Focal Length 1 112.17  2 4 12.77  3 6 −10.33    4 8 8.00 5 10  −92.74    6 12  199.91  714  −10.18    Lens Composite Focal Length First Lens-Second Lens 6.49Fourth Lens-Fifth Lens 10.77  Sixth Lens-Seventh Lens −12.11    AsphericSurface Data 1st Surface 2nd Surface 4th Surface 5th Surface 6th Surface7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+00 0.000E+00−2.783E+01   −7.256E+00   0.000E+00 A4 −8.273E−03   −9.963E−03  5.816E−03 3.443E−03 −1.061E−02   −3.471E−03   −5.906E−03   A6−2.605E−03   −2.187E−04   −8.235E−04   −2.066E−03   −2.861E−04  8.096E−04 1.742E−03 A8 0.000E+00 0.000E+00 0.000E+00 −1.004E−03  −8.302E−05   2.716E−04 0.000E+00 A10 0.000E+00 0.000E+00 0.000E+003.321E−04 1.942E−04 −1.350E−04   0.000E+00 A12 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 2.580E−05 0.000E+00 A14 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 A160.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+009th Surface 10th Surface 11th Surface 12th Surface 13th Surface 14thSurface 15th Surface k 0.000E+00 0.000E+00 −9.979E−01   0.000E+000.000E+00 0.000E+00 0.000E+00 A4 −9.927E−04   2.847E−02 −1.491E−03  −2.009E−02   −1.310E−02   −8.896E−03   −9.550E−03   A6 1.172E−03−1.587E−03   3.939E−04 8.868E−04 2.096E−04 3.261E−04 2.211E−04 A80.000E+00 0.000E+00 −2.078E−04   −1.527E−04   −1.462E−05   0.000E+004.801E−06 A10 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+000.000E+00 −1.574E−07   A12 0.000E+00 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 −2.691E−09   A14 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 9.923E−11 A16 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 −1.248E−12  

As shown in Table 11, the imaging lens according to Example 9 satisfiesall the conditional expressions (1) to (8).

FIG. 26 shows various aberrations of the imaging lens according toExample 9 in which the object is at infinity, and FIG. 27 shows variousaberrations of the imaging lens according to Example 9 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 26 and 27, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andrelatively high brightness with an F-value of 2.6. The ratio of totaltrack length TTL to maximum image height ih (TTL/2ih) is 0.82, so itoffers a compact design though it uses seven constituent lenses.

Example 10

The basic lens data of Example 10 is shown below in Table 10.

TABLE 10 Example 10 in mm f = 7.36 Fno = 2.5 ω(°) = 38.7 ih = 5.99 TTL =9.50 Surface Data Surface No. i Curvature Radius r Surface Distance dRefractive Index Nd Abbe Number vd (Object Surface) Infinity Infinity 1* 4.082 0.546 1.5438 55.57  2* −40.974    0.075  3 (Stop) Infinity0.160  4* −6.249   0.441 1.5438 55.57  5* −6.657   0.018  6* 4.596 0.3431.6349 23.97  7* 2.641 0.257  8* 5.491 0.548 1.5438 55.57  9* −39.207   1.047 10* −2.412   1.469 1.5438 55.57 11* −2.404   0.020 12* 6.345 1.5681.5438 55.57 13* 4.741 1.186 14*  −5.6141   0.794 1.6142 25.58 15*−65.3607   0.250 16 Infinity 0.210 1.5168 64.20 17 Infinity 0.638 ImagePlane Infinity Constituent Lens Data Lens Start Surface Focal Length 1 16.86 2 4 −302.62    3 6 −10.49    4 8 8.90 5 10  20.28  6 12  −52.62   7 14  −10.05    Lens Composite Focal Length First Lens-Second Lens 7.17Fourth Lens-Fifth Lens 7.69 Sixth Lens-Seventh Lens −8.93   AsphericSurface Data 1st Surface 2nd Surface 4th Surface 5th Surface 6th Surface7th Surface 8th Surface k 0.000E+00 0.000E+00 0.000E+00 0.000E+00−2.719E+01   −7.225E+00   0.000E+00 A4 −7.900E−03   −7.942E−03  1.650E−02 2.599E−03 −1.253E−02   −4.166E−03   −5.588E−03   A6−3.056E−03   2.148E−03 1.728E−03 −1.640E−03   −2.547E−04   1.597E−039.647E−04 A8 −3.141E−04   0.000E+00 0.000E+00 −1.566E−03   3.480E−044.406E−04 0.000E+00 A10 0.000E+00 0.000E+00 0.000E+00 4.313E−048.883E−05 −1.358E−04   0.000E+00 A12 0.000E+00 0.000E+00 0.000E+000.000E+00 0.000E+00 2.231E−05 0.000E+00 A14 0.000E+00 0.000E+000.000E+00 0.000E+00 0.000E+00 −7.263E−07   0.000E+00 A16 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 9th Surface10th Surface 11th Surface 12th Surface 13th Surface 14th Surface 15thSurface k 0.000E+00 0.000E+00 −7.921E−01   0.000E+00 0.000E+00 0.000E+000.000E+00 A4 7.101E−03 1.848E−02 −2.652E−03   −1.829E−02   −1.209E−02  1.274E−03 −4.969E−03   A6 8.746E−04 −1.959E−03   5.219E−04 6.593E−044.187E−04 9.132E−06 1.683E−04 A8 0.000E+00 3.805E−04 −1.145E−04  −7.584E−05   −1.751E−05   0.000E+00 −4.212E−07   A10 0.000E+00 0.000E+000.000E+00 0.000E+00 6.682E−08 0.000E+00 −1.586E−08   A12 0.000E+000.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 −1.086E−09   A140.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 −1.717E−11  A16 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+002.057E−13

As shown in Table 11, the imaging lens according to Example 10 satisfiesall the conditional expressions (1) to (8).

FIG. 29 shows various aberrations of the imaging lens according toExample 10 in which the object is at infinity, and FIG. 30 shows variousaberrations of the imaging lens according to Example 10 in which theentire imaging lens is extended for autofocusing and the distance of theobject is 150 mm. As shown in FIGS. 29 and 30, various aberrations arecorrected properly.

The imaging lens provides a wide field of view of nearly 80 degrees andhigh brightness with an F-value of 2.5. The ratio of total track lengthTTL to maximum image height ih (TTL/2ih) is 0.79, so it offers a compactdesign though it uses seven constituent lenses.

As explained above, the imaging lenses according to the preferredembodiment of the present invention realize an imaging lens system whichprovides a wide field of view of nearly 80 degrees and relatively highbrightness with an F-value of 2.4 to 2.6 and which, when the entireimaging lens is extended for autofocusing, corrects aberrations properlyin both imaging of an object at infinity and imaging of an object atclose range. In addition, the ratio of total track length TTL to maximumimage height ih (TTL/2ih) is 0.8 or so, offering a compact lens system.

Table 11 shows data on Examples 1 to 10 in relation to the conditionalexpressions (1) to (8).

TABLE 11 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Example 7 Example 8 Example 9 Example 10 Conditional 7.09 6.97 7.00 6.576.85 6.74 6.01 6.77 6.49 7.17 Expression (1) 0 < f12 Conditional 0.940.93 0.93 0.86 0.92 0.90 0.80 0.92 0.87 0.97 Expression (2) 0.6 < f12/f< 1.3 Conditional −1.41 −1.42 −1.38 −1.31 −1.29 −1.36 −1.86 −1.44 −1.38−1.42 Expression (3) −2.2 < f3/f < −1.0 Conditional 1.06 1.07 1.08 0.831.02 1.05 1.81 1.10 1.44 1.04 Expression (4) 0.6 < f45/f < 2.2Condidonal −1.27 −1.13 −1.40 −0.78 −1.13 −1.16 −1.31 −1.20 −1.62 −1.21Expression (5) −2.0 < f67/f < −0.6 Conditional 55.57 55.57 55.57 55.5755.57 55.57 55.57 55.57 55.57 55.57 Expression (6) 50 < vd1 < 70Conditional 55.57 55.57 55.57 55.57 55.57 55.57 55.57 55.57 55.57 55.57Expression (7) 50 < vd2 < 70 Conditional 23.97 23.97 23.97 23.97 23.9723.97 23.97 23.97 23.97 23.97 Expression (3) 20 < vd3 < 30

The imaging lens composed of seven constituent lenses according to thepresent invention features compactness and a wide field of view andmeets the demand for high resolution images. In particular, when it isused in a highly functional product such as a smart TV or 4K TV, or aninformation terminal such as a game console or PC, or a mobile terminalsuch as a smart phone or mobile phone with a professional qualitydigital camera function or PDA (Personal Digital Assistant), it enhancesthe performance of the product in which it is mounted.

The effects of the present invention are as follows.

According to the present invention, it is possible to provide a compactimaging lens which delivers higher optical performance than existingimaging lenses when it is used not only in a conventional small imagesensor but also in a large image sensor and can correct variousaberrations properly in both imaging of an object at infinity andimaging of an object at close range even though it provides a wide fieldof view.

1-20. (canceled)
 21. An imaging lens for a solid-state image sensor, comprising in order from an object side to an image side of the imaging lens: a first lens having positive refractive power; a second lens having positive or negative refractive power; a third lens having negative refractive power; a fourth lens that is a double-sided aspheric lens having positive or negative refractive power; a fifth lens that is a double-sided aspheric lens having positive or negative refractive power; a sixth lens that is a double-sided aspheric lens having positive or negative refractive power; a seventh lens that is a double-sided aspheric lens having negative refractive power; and air gaps disposed between each pair of adjacent lenses, wherein the imaging lens has a total of seven single lenses, and the sixth lens has a concave surface on the image side near an optical axis.
 22. The imaging lens according to claim 21, wherein a conditional expression (1) below is satisfied: 0<f12  (1) where f12: a composite focal length of the first lens and the second lens.
 23. The imaging lens according to claim 21, wherein the third lens is a double-sided aspheric lens and has a concave surface on the image side near an optical axis.
 24. The imaging lens according to claim 21, wherein the fourth lens is a biconvex lens having a convex surface on the object side near an optical axis or a meniscus lens having a convex surface on the object side.
 25. The imaging lens according to claim 21, wherein an image-side surface of the sixth lens has an aspheric shape in which a portion near an optical axis has a concave shape and the concave shape changes to a convex shape in a peripheral portion distant from the optical axis.
 26. The imaging lens according to claim 21, wherein a conditional expression (2) below is satisfied: 0.6<f12/f<1.3  (2) where f12: a composite focal length of the first lens and the second lens, and f: a focal length of the overall optical system of the imaging lens.
 27. The imaging lens according to claim 21, wherein a conditional expression (3) below is satisfied: −2.2<f3/f<−1.0  (3) where f3: a focal length of the third lens, and f: a focal length of the overall optical system of the imaging lens.
 28. The imaging lens according to claim 21, wherein a conditional expression (4) below is satisfied: 0.6<f45/f<2.2  (4) where f45: a composite focal length of the fourth lens and the fifth lens, and f: a focal length of the overall optical system of the imaging lens.
 29. The imaging lens according to claim 21, wherein a conditional expression (5) below is satisfied: −2.0<f67/f<−0.6  (5) where f67: a composite focal length of the sixth lens and the seventh lens, and f: a focal length of the overall optical system of the imaging lens.
 30. The imaging lens according to claim 21, wherein conditional expressions (6) to (8) below are satisfied: 50<νd1<70  (6) 50<νd2<70  (7) 20<νd3<30  (8) where νd1: Abbe number of the first lens at d-ray, νd2: Abbe number of the second lens at d-ray, and νd3: Abbe number of the third lens at d-ray.
 31. An imaging lens for a solid-state image sensor, comprising in order from an object side to an image side of the imaging lens: a first lens having positive refractive power; a second lens having positive refractive power; a third lens having negative refractive power; a fourth lens that is a double-sided aspheric lens having positive or negative refractive power; a fifth lens that is a double-sided aspheric lens having positive or negative refractive power; a sixth lens that is a double-sided aspheric lens having positive or negative refractive power; a seventh lens that is a double-sided aspheric lens having negative refractive power; and air gaps disposed between each pair of adjacent lenses, wherein the third lens has a convex surface on the object side near an optical axis.
 32. The imaging lens according to claim 31, wherein a conditional expression (1) below is satisfied: 0<f12  (1) where f12: a composite focal length of the first lens and the second lens.
 33. The imaging lens according to claim 31, wherein the third lens is a double-sided aspheric lens and has a concave surface on the image side near an optical axis.
 34. The imaging lens according to claim 31, wherein the fourth lens is a biconvex lens having a convex surface on the object side near an optical axis or a meniscus lens having a convex surface on the object side.
 35. The imaging lens according to claim 31, wherein an image-side surface of the sixth lens has an aspheric shape in which a portion near an optical axis has a concave shape and the concave shape changes to a convex shape in a peripheral portion distant from the optical axis.
 36. The imaging lens according to claim 31, wherein a conditional expression (2) below is satisfied: 0.6<f12/f<1.3  (2) where f12: a composite focal length of the first lens and the second lens, and f: a focal length of the overall optical system of the imaging lens.
 37. The imaging lens according to claim 31, wherein a conditional expression (3) below is satisfied: −2.2<f3/f<−1.0  (3) where f3: a focal length of the third lens, and f: a focal length of the overall optical system of the imaging lens.
 38. The imaging lens according to claim 31, wherein a conditional expression (4) below is satisfied: 0.6<f45/f<2.2  (4) where f45: a composite focal length of the fourth lens and the fifth lens, and f: a focal length of the overall optical system of the imaging lens.
 39. The imaging lens according to claim 31, wherein a conditional expression (5) below is satisfied: −2.0<f67/f<−0.6  (5) where f67: a composite focal length of the sixth lens and the seventh lens, and f: a focal length of the overall optical system of the imaging lens.
 40. The imaging lens according to claim 31, wherein conditional expressions (6) to (8) below are satisfied: 50<νd1<70  (6) 50<νd2<70  (7) 20<νd3<30  (8) where νd1: Abbe number of the first lens at d-ray, νd2: Abbe number of the second lens at d-ray, and νd3: Abbe number of the third lens at d-ray. 